hide in a bush, and initiate w/ your knock in the air move, then u should like 3 hit him.. or just wait for someone else to intiate then kill him.. or just get more Magic Resist.. so u can tank the damage and then roflstomp his squishy ass.

Your only way to escape from his ultimate is using Quicksilver. Try to move a lot, if Malzahar waste his spells he's very weak, And more if you're using Xin. Try getting a Quicksilver next time, and try to walk in random directions to avoid the Null Zone or Call of the Void